CHEM 2332H Lecture : Lecture 252014.pdf
15 Jul 2014
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Document Summary
Develop mo for aromatics & anti-aromatics & use polygon rule. Not just resonance that helps benzene, need to look @ mo. Mo for benezene: 6 atomic orbitals (p) and 6 electrons. Many ways to put 1 node since it"s a hexagon. Right: 4 bonding, 2 antibonding, (nonbonding when you pair opposite angles) --> net 2 bonding. *if they"re closest neighbors, then antibonding, or else, nonbindng donut ------> (all phases lined up) Nonbonding b/c all bonds and antibonds cancel out. After filling up electrons --------> suggests that cyclobutadiene should actually have radicals. --> not very stablethat"s why it has higher energy and can"t be isolated. Polygon rule: (the shapes in the red = the shapes of the cyclomolecule) Mo for regular, completely conjugated cyclic system has the same polygonal shape as the compound as long as you have 1 vertex @ bottom.
